This invention relates to an environmental hood for collecting pollutants and more particularly to a truck hood for capturing and collecting dust and other pollutants from a truck filling operation in which the truck is being filled with particulate matter.
In the typical batch plant for filling transit mix cement trucks the individual trucks generally are filled with a dry mix of the appropriate materials from the batch plant from a hopper or series of hoppers which introduce the materials into the truck mixer drum through a chute directed into the mouth of the mixer drum. The water stream for the mix is generally narrow and may be introduced after the dry materials. Even when introduced simultaneously there still is a significant amount of airborne dust created in the filling operation. Since trucks come in all sizes and shapes with filling being accomplished anywhere from the front to the back of the truck, depending on make and model, the problem of capturing dust from the dry particulate materials to meet current environmental standards has become more and more difficult. A batch plant to be successful must be able to service a wide variety of truck types and styles and yet must also meet the increasingly tight environmental regulations as to dust and other pollutant emissions.
In the past, various types of hoods have been proposed and used under certain conditions for enclosing the filling end of a truck when the dry particulate materials are fed into the truck. The dust created is generally removed through an exhaust system which usually includes a filter bag house of some type to filter out the dust and other contaminate material from the exhaust air. The exhaust hoods have been limited in use and application because of the difficulty the batch operator and truck driver have encountered in maneuvering the truck into proper position under the exhaust hood. Drivers have been particularly concerned with not being able to see the filling chute and therefore have had considerable difficulty in properly aligning the truck. As a result the hoods heretofore available have been frequently damaged or completely neglected because of the difficulty of use. Also a number of prior art hoods have required that the truck be backed into them which because of the size and complexity of transit mix trucks makes this is a particularly difficult task. Some efforts have been made to provide drive through hood arrangements but it has been particularly difficult to properly capture the dust at the filling point of the truck with this type of enclosure.